1. Field of the Invention
The subject matter described herein concerns the transmission of packet data calls and more particularly, the retry of the transmission of packet data calls.
2. Description of the Related Art
Currently, many mobile units have the capability of conducting packet data calls in which voice is carried over data packets, as opposed to a circuit-switched call. For example, a number of mobile units conduct packet data calls using the telecommunications standard Evolution-Data Optimized, or EVDO, which is part of the CDMA2000 family of standards. Another protocol that belongs to CDMA2000 is 1X Radio Transmission Technology (RTT), or simply 1X. When using 1X, a mobile unit may transmit data or voice over a packet data network. There are several existing handsets that have the capability of transmitting packet data using EVDO or 1X. EVDO has higher transmit speeds, however, and is preferred over 1X when transmitting packet data.
As part of the transmission of packet data and as known in the art, a mobile unit may perform Mobile Internet Protocol (MIP) or Simple Internet Protocol (SIP) registration on the EVDO network. Typically, because MIP registration allows the mobile unit to maintain a permanent IP address when moving from one network to another, the mobile unit will attempt MIP registration on the EVDO network first. If this registration does not succeed, then the mobile unit will attempt SIP registration on the EVDO network. If the SIP registration fails, then the mobile unit will wait a predetermined amount of time before attempting another round of MIP/SIP registrations on EVDO. In certain circumstances, the cause of the registration failures is a failure in the data link layer of the EVDO network. This failure in the data link layer, however, may not affect the operation of the physical layer of the EVDO network. Because the physical layer is unaffected, the mobile unit will simply continue with the attempted MIP/SIP registrations on the EVDO network. After all the attempts have been exhausted, the mobile unit will abort the attempted call.